|
In the five-year trial that randomly assigned women to different
kinds of diets, those instructed to eat a Mediterranean-style diet
with four tablespoons of extra virgin olive oil per day had about
half as many breast cancer diagnoses as those on a low-fat diet.
“With an overall healthy diet plus extra virgin olive oil there is a
reduction in the hard endpoint of breast cancer,” said senior author
Dr. Miguel A. Martinez-Gonzalez of the University of Navarra in
Pamplona and CIBEROBN in Madrid.
“We have now evidence to support that olive oil is causally related
to reduction in risk of breast cancer,” he said.
The fact that the findings are based on a randomized trial, the
gold-standard of research, “immediately impressed” the journal
editors, writes Dr. Mitchell H. Katz, deputy editor of JAMA Internal
Medicine, in an editor’s note accompanying the study.
Still, the authors caution in their report, the data come from a
larger long-term trial whose primary focus is heart disease. And out
of more than 4,000 women included in the breast cancer study, there
were only 35 cases of breast cancer, a low number of total cases for
statistical analysis. This and a lack of data about cancer-screening
mammograms among the women limit the results, they write.
Martinez-Gonzalez and colleagues studied breast cancer outcomes in
women participating in PREDIMED, a study of the Mediterranean diet’s
protective effects against cardiovascular disease and a variety of
other illnesses (see Reuters Health story of May 11, 2015 here:
http://reut.rs/1RyZALT).
Between 2003 and 2009, a total of 4,282 women ages 60 to 80 years
old with a high risk of cardiovascular disease were randomly
assigned to a Mediterranean diet supplemented with extra virgin
olive oil, the same diet supplemented with nuts or to a comparison
group that was told to reduce their overall dietary fat intake.
Those in the two Mediterranean diet groups were given either one
liter (34 ounces) of olive oil per week or 30 grams (1 ounce) of
nuts per day for free. The olive oil group was instructed to consume
about 50 grams (4.2 tablespoons) per day, including in cooked foods
and on salads or bread.
The women had quarterly sessions with dieticians, completing
questionnaires that gauged how well they were following their
assigned diet. There was no specific advice to reduce overall
calorie intake or to increase physical activity.
A Mediterranean diet is a plant-based diet that replaces most
desserts with fruit, limits beverage intake to mostly water or red
wine, reduces dairy intake and keeps red meat consumption to once a
week or less, Martinez-Gonzalez said.
[to top of second column] |
Over the course of the study, there were 17 confirmed diagnoses of
breast cancer in the low-fat comparison group, 10 in the
Mediterranean diet with nuts group and eight in the Mediterranean
diet with olive oil group, the researchers found.
There is some evidence with animal studies that extra virgin olive
oil, which is rich in polyphenols, may induce programmed cell death
or early cancer cells in the breast, Martinez-Gonzalez told Reuters
Health.
“It is definitively important to assess with new trials the
transferability of a Mediterranean diet to other countries,” he
said. “Here our participants were very happy, we provided olive oil
for free and gave shopping lists and written materials.”
Done correctly, the Mediterranean diet is delicious and much more
enjoyable than a low-fat diet, he said.
There were no apparent negative side effects of the dietary change,
he said.
“At the beginning it is tough, but little by little participants
change in the right direction and they enjoy the cooking procedure,”
he said.
The study had many limitations, but a Mediterranean diet is safe and
does reduce the risk of cardiovascular disease, Katz writes. “It may
also prevent breast cancer. We hope to see more emphasis on
Mediterranean diet to reduce cancer and cardiovascular disease and
improve health and well-being.”
SOURCE: http://bit.ly/1FIOhZn and http://bit.ly/1URkkx6 JAMA
Internal Medicine, online September 14, 2015.
[© 2015 Thomson Reuters. All rights
reserved.] Copyright 2015 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed. |
